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25 Mar 2021

Role Of Gut Microbiota In Travel-Related Acquisition Of Extended Spectrum β-lactamase-Producing Enterobacteriaceae

What a week for the Tun Lab! 
 
After their publication in Gastroenterology and the award they received at the 2021 Inventions Geneva Evaluation Days for the “Innovative Sewage Testing Tool for SARS-CoV-2” project, Hein Min Tun and PhD student Ye Peng publish in the Journal of Travel Medicine (Oxford Academic) about the role of gut microbiota in the acquisition of antimicrobial resistant bacteria during international travels. 
 
 
Abstract
Background
International travel could facilitate the spread of antimicrobial-resistant bacteria including extended spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E). Previous studies, which attempted to understand the role of gut microbiota in the acquisition of antimicrobial resistant bacteria during international travels, are limited to western travellers.


Methods
We established a prospective cohort of 90 Hong Kong travellers to investigate gut microbiota determinants and associated risk factors for the acquisition of ESBL-E. Baseline characteristics and travel-associated risk factors were gathered through questionnaires. Faecal samples were collected in 3-4 days before and after travel. Antimicrobial susceptibility of ESBL-E isolates was tested, and gut microbiota were profiled by 16S rDNA amplicon sequencing. Non-parametric tests were used to detect potential associations, and logistic regression models were used to quantify the associations. Random forest models were constructed to identify microbial predictors for ESBL-E acquisition.


Results
In total, 49 (54.4%) participants were tested negative for ESBL-E colonization before travel and were followed up after travel. A total of 60 ESBL-E isolates were cultured from 20 (40.8%) participants. Having low Actinobacteria richness and low abundance of short-chain fatty acid-producing bacteria in the gut microbiota before travel increased the risk of acquiring ESBL-E and the risk can be further exacerbated by eating raw seafood during travel. Besides, post-travel ESBL-E positive participants had increased abundances of several opportunistic pathogens such as Staphylococcus, Enterococcus, Escherichia/Shigella and Klebsiella. The random forest model integrating pre-travel microbiota and the identified travel-related risk factor could predict ESBL-E acquisition with an area under the curve of 75.4% (95% confidence interval: 57.9–93.0%).


Conclusions
In this study, we identified both travel-related risk factors and microbiota predictors for the risk of ESBL-E acquisition. Our results provide foundational knowledge for future developments of microbiota-based interventions to prevent ESBL-E acquisition during international travels.
 

24 Mar 2021

Ethnicity Associations With Food Sensitization Are Mediated By Gut Microbiota Development In The First Year Of Life

New publication from the Tun Lab! 
Dr Hein Min Tun, Ye Peng (PhD student) and team published in Gastroenterology about the relationship between food sensitization and the development of gut microbiota during the first year of life, with fellow colleagues from University of Alberta and University of Toronto, Canada, within the CHILD Cohort Study, a robust Canadian research platform to understand development of disease so it can be predicted, prevented or better treated.
 
 
 
Abstract
Background and aims: Increasing evidence supports the role of early-life gut microbiota in developing atopic diseases, but ecological changes to gut microbiota during infancy in relation to food sensitization remain unclear. We aimed to characterize and associate these changes with the development of food sensitization in children.
 
Methods: In this observational study, using 16S rRNA amplicon sequencing, we characterized the composition of 2844 fecal microbiota in 1422 Canadian full-term infants. Atopic sensitization outcomes were measured by skin prick tests at age 1 year and 3 years. The association between gut microbiota trajectories, based on longitudinal shifts in community clusters, and atopic sensitization outcomes at age 1 and 3 years was determined. Ethnicity and early life exposures influencing microbiota trajectories were initially examined, and post hoc analyses were conducted.
 
Results: Four identified developmental trajectories of gut microbiota were shaped by birth mode and varying by ethnicity. The trajectory with persistently-low Bacteroides abundance and high Enterobacteriaceae/Bacteroidaceae ratio throughout infancy increased the risk of sensitization to food allergens, particularly peanut at age 3 years by 3-fold (adjusted OR, 2.82; 95% CI, 1.13-7.01); a much higher likelihood for peanut sensitization was found if infants with this trajectory were born to Asian mothers (adjusted OR, 7.87; 95% CI, 2.75-22.55). It was characterized by a deficiency in sphingolipid metabolism and persistent C. difficile colonization. Importantly, this trajectory of depleted Bacteroides abundance mediated the association between Asian ethnicity and food sensitization.
 
Conclusions: This study documented an association between persistently-low gut Bacteroides abundance throughout infancy and sensitization to peanut in childhood. It is the first to show a mediation role for infant gut microbiota in ethnicity-associated development of food sensitization.
 

18 Feb 2021

HKU-Pasteur In Best of Cell Reports 2020 List

Cell Reports anounced its Best of 2020 list, highlighting the jounrnal's major and most impactful publications of the past year. 

Amongst 12 publications, from axonal ribosomes to imaging of brain activity during human behavior, and from a Review article on microglia to new roles for p53 in cancer immunology, we can find Tomas Lv and Chris Mok's paper Cross-Reactive Antibody Response Between Sars-Cov-2 and Sars-Cov Infections.

Summary:

The World Health Organization has declared the ongoing outbreak of COVID-19, which is caused by a novel coronavirus SARS-CoV-2, a pandemic. There is currently a lack of knowledge about the antibody response elicited from SARS-CoV-2 infection. One major immunological question concerns antigenic differences between SARS-CoV-2 and SARS-CoV. We address this question by analyzing plasma from patients infected by SARS-CoV-2 or SARS-CoV and from infected or immunized mice. Our results show that, although cross-reactivity in antibody binding to the spike protein is common, cross-neutralization of the live viruses may be rare, indicating the presence of a non-neutralizing antibody response to conserved epitopes in the spike. Whether such low or non-neutralizing antibody response leads to antibody-dependent disease enhancement needs to be addressed in the future. Overall, this study not only addresses a fundamental question regarding antigenicity differences between SARS-CoV-2 and SARS-CoV but also has implications for immunogen design and vaccine development.

10 Feb 2021

Cupric Oxide Coating That Rapidly Reduces Infection by SARS-CoV-2 via Solids

Leo Poon, Co-Director at HKU-Pasteur, and Alex Chin, Alex Chin, investigator in Professor Poon’s team, just published the new developments of their projects on surface coating conducted with Professor William Ducker of the Department of Engineering at Virginia Tech.

In this follow-up study, Prof. Ducker’s group has developed another copper-bearing coating containing cupric oxide (CuO) that targets to reduce the infectivity of SARS-CoV-2 on a contaminated surface. 

The project resulted in the development of a porous and hydrophilic coating that can be coated on smooth surfaces such as glass. The hydrophilic property of the coating is long-lasting and allows efficient imbibition of a droplet to increase the surface area of contact. 

The coating could reduce the infectivity of SARS-CoV-2 by 99.9% in 1 hour, whereas control glass without coating required 2 days to achieve the same level of reduction in virus infectivity. The efficiency was even higher with a thicker coating that reduced the infectivity of the virus within 30 min. The team believe this coating can be applied to common touch surfaces to reduce the risk of COVID-19 transmission via indirect contact.

>>> Read the full publication: Cupric Oxide Coating That Rapidly Reduces Infection by SARS-CoV-2 via Solids

26 Jan 2021

Investigation of the antibody landscape in children: SARS-CoV-2 infected children have lower levels of antibodies than adults

Children are less clinically affected by SARS-CoV-2 infection than adults with the majority of cases being mild or asymptomatic and the differences in infection outcomes are poorly understood. The kinetics, magnitude and landscape of the antibody response may impact the clinical severity and serological diagnosis of COVID-19. Thus, a comprehensive investigation of the antibody landscape in children and adults is needed.

This investigation has been conducted by Asmaa Hachim and Niloufar Kavian within Sophie Valkenburg’s team in a pre-print publication published online on January 3rd. The research team tested 254 plasma from 122 children with symptomatic and asymptomatic SARS-CoV-2 infections in Hong Kong. Adult COVID-19 patients and pre-pandemic controls were included for comparison.

Therefore, this is the most comprehensive study to date of the magnitude, specificity and duration of SARS-CoV-2 specific antibodies in children.

The results show that children have lower levels of antibodies to the majority of proteins overall, with minor responses to non-structural proteins. The study highlights that SARS-CoV-2 antibody response in children is highly diverse, which may be an important factor in driving control of SARS-CoV-2 infection.

 

 

Read the publication online: “The SARS-CoV-2 antibody landscape is lower in magnitude for structural proteins, diversified for accessory proteins and stable long-term in children”, medRxiv 2021.01.03.21249180.

12 Jan 2021

Follow-up: Project On Sewage Helps Uncover Nine Infections In Hong Kong

The University of Hong Kong sewage surveillance project involving HKU-Pasteur research teams will extend its screening capacity after successfully uncovering hidden COVID-19 carriers in two housing blocks in Hong Kong. Standard operating procedure are finalised to trigger mandatory testing of all residents in a block if sewage checks reveal two consecutive positive results or two positive results over three days.

Sponsored by the Health and Medical Research Fund (HMRF) under the Food and Health Bureau, this project allowed the collection of more than 300 domestic sewage samples from sewage collection systems in different areas for nucleic acid tests of the new coronavirus SARS-CoV-2. 
 
Since the beginning of the project in October 2020, the team has been able to demonstrate that sewage surveillance could provide early warning of COVID-19 outbreaks, reflecting the overall spread of virus in the community. It also helps tracking the development trend of community outbreak.
 
 
 
 

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